In recent years, as display panels, liquid crystal display panels have been developed. They are featured in that they are light and thin and also have high resolution. In general, a liquid crystal display panel comprises an array substrate, a counter-substrate disposed opposite to the array substrate, with a predetermined gap therebetween, a sealing member by which the array substrate and the counter-substrate are joined to each other, and a liquid crystal layer formed in a space surrounded by the array substrate, the counter-substrate and the sealing member.
The array substrate and the counter-substrate include respective alignment films contacting the liquid crystal layer. The alignment films are subjected to rubbing. Thereby, the alignment films can control initial alignment of liquid crystal molecules.
It should be noted that in the case where alignment films are subjected to rubbing, the following problems arise: an element (TFT) is broken by static electricity generating due to friction; and a display failure (disorder in alignment of liquid crystal molecules) occurs due to dust generated by the rubbing. In order to solve those problems occurring due to the rubbing, it is studied what method is applicable as a so-called rubbing-less alignment method for controlling alignment of liquid crystal molecules without rubbing.
In view of the above, it is studied whether photo alignment treatment is applicable as a rubbing-less alignment method for obtaining a liquid crystal display panel which is high in manufacturing yield and display quality. The photo alignment treatment can be carried out by radiating linearly polarized light onto an alignment film. Thereby, the alignment film subjected to the photo alignment treatment can control initial alignment of liquid crystal molecules.